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| 1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. | |
| 2 // Use of this source code is governed by a BSD-style license that can be | |
| 3 // found in the LICENSE file. | |
| 4 | |
| 5 #include "crypto/rsa_private_key.h" | |
| 6 | |
| 7 #include <stddef.h> | |
| 8 #include <stdint.h> | |
| 9 | |
| 10 #include <algorithm> | |
| 11 | |
| 12 #include "base/logging.h" | |
| 13 #include "base/memory/scoped_ptr.h" | |
| 14 #include "base/strings/string_util.h" | |
| 15 | |
| 16 // This file manually encodes and decodes RSA private keys using PrivateKeyInfo | |
| 17 // from PKCS #8 and RSAPrivateKey from PKCS #1. These structures are: | |
| 18 // | |
| 19 // PrivateKeyInfo ::= SEQUENCE { | |
| 20 // version Version, | |
| 21 // privateKeyAlgorithm PrivateKeyAlgorithmIdentifier, | |
| 22 // privateKey PrivateKey, | |
| 23 // attributes [0] IMPLICIT Attributes OPTIONAL | |
| 24 // } | |
| 25 // | |
| 26 // RSAPrivateKey ::= SEQUENCE { | |
| 27 // version Version, | |
| 28 // modulus INTEGER, | |
| 29 // publicExponent INTEGER, | |
| 30 // privateExponent INTEGER, | |
| 31 // prime1 INTEGER, | |
| 32 // prime2 INTEGER, | |
| 33 // exponent1 INTEGER, | |
| 34 // exponent2 INTEGER, | |
| 35 // coefficient INTEGER | |
| 36 // } | |
| 37 | |
| 38 namespace { | |
| 39 // Helper for error handling during key import. | |
| 40 #define READ_ASSERT(truth) \ | |
| 41 if (!(truth)) { \ | |
| 42 NOTREACHED(); \ | |
| 43 return false; \ | |
| 44 } | |
| 45 } // namespace | |
| 46 | |
| 47 namespace crypto { | |
| 48 | |
| 49 const uint8_t PrivateKeyInfoCodec::kRsaAlgorithmIdentifier[] = { | |
| 50 0x30, 0x0D, 0x06, 0x09, 0x2A, 0x86, 0x48, 0x86, | |
| 51 0xF7, 0x0D, 0x01, 0x01, 0x01, 0x05, 0x00}; | |
| 52 | |
| 53 PrivateKeyInfoCodec::PrivateKeyInfoCodec(bool big_endian) | |
| 54 : big_endian_(big_endian) {} | |
| 55 | |
| 56 PrivateKeyInfoCodec::~PrivateKeyInfoCodec() {} | |
| 57 | |
| 58 bool PrivateKeyInfoCodec::Export(std::vector<uint8_t>* output) { | |
| 59 std::list<uint8_t> content; | |
| 60 | |
| 61 // Version (always zero) | |
| 62 uint8_t version = 0; | |
| 63 | |
| 64 PrependInteger(coefficient_, &content); | |
| 65 PrependInteger(exponent2_, &content); | |
| 66 PrependInteger(exponent1_, &content); | |
| 67 PrependInteger(prime2_, &content); | |
| 68 PrependInteger(prime1_, &content); | |
| 69 PrependInteger(private_exponent_, &content); | |
| 70 PrependInteger(public_exponent_, &content); | |
| 71 PrependInteger(modulus_, &content); | |
| 72 PrependInteger(&version, 1, &content); | |
| 73 PrependTypeHeaderAndLength(kSequenceTag, content.size(), &content); | |
| 74 PrependTypeHeaderAndLength(kOctetStringTag, content.size(), &content); | |
| 75 | |
| 76 // RSA algorithm OID | |
| 77 for (size_t i = sizeof(kRsaAlgorithmIdentifier); i > 0; --i) | |
| 78 content.push_front(kRsaAlgorithmIdentifier[i - 1]); | |
| 79 | |
| 80 PrependInteger(&version, 1, &content); | |
| 81 PrependTypeHeaderAndLength(kSequenceTag, content.size(), &content); | |
| 82 | |
| 83 // Copy everying into the output. | |
| 84 output->reserve(content.size()); | |
| 85 output->assign(content.begin(), content.end()); | |
| 86 | |
| 87 return true; | |
| 88 } | |
| 89 | |
| 90 bool PrivateKeyInfoCodec::ExportPublicKeyInfo(std::vector<uint8_t>* output) { | |
| 91 // Create a sequence with the modulus (n) and public exponent (e). | |
| 92 std::vector<uint8_t> bit_string; | |
| 93 if (!ExportPublicKey(&bit_string)) | |
| 94 return false; | |
| 95 | |
| 96 // Add the sequence as the contents of a bit string. | |
| 97 std::list<uint8_t> content; | |
| 98 PrependBitString(&bit_string[0], static_cast<int>(bit_string.size()), | |
| 99 &content); | |
| 100 | |
| 101 // Add the RSA algorithm OID. | |
| 102 for (size_t i = sizeof(kRsaAlgorithmIdentifier); i > 0; --i) | |
| 103 content.push_front(kRsaAlgorithmIdentifier[i - 1]); | |
| 104 | |
| 105 // Finally, wrap everything in a sequence. | |
| 106 PrependTypeHeaderAndLength(kSequenceTag, content.size(), &content); | |
| 107 | |
| 108 // Copy everything into the output. | |
| 109 output->reserve(content.size()); | |
| 110 output->assign(content.begin(), content.end()); | |
| 111 | |
| 112 return true; | |
| 113 } | |
| 114 | |
| 115 bool PrivateKeyInfoCodec::ExportPublicKey(std::vector<uint8_t>* output) { | |
| 116 // Create a sequence with the modulus (n) and public exponent (e). | |
| 117 std::list<uint8_t> content; | |
| 118 PrependInteger(&public_exponent_[0], | |
| 119 static_cast<int>(public_exponent_.size()), | |
| 120 &content); | |
| 121 PrependInteger(&modulus_[0], static_cast<int>(modulus_.size()), &content); | |
| 122 PrependTypeHeaderAndLength(kSequenceTag, content.size(), &content); | |
| 123 | |
| 124 // Copy everything into the output. | |
| 125 output->reserve(content.size()); | |
| 126 output->assign(content.begin(), content.end()); | |
| 127 | |
| 128 return true; | |
| 129 } | |
| 130 | |
| 131 bool PrivateKeyInfoCodec::Import(const std::vector<uint8_t>& input) { | |
| 132 if (input.empty()) { | |
| 133 return false; | |
| 134 } | |
| 135 | |
| 136 // Parse the private key info up to the public key values, ignoring | |
| 137 // the subsequent private key values. | |
| 138 uint8_t* src = const_cast<uint8_t*>(&input.front()); | |
| 139 uint8_t* end = src + input.size(); | |
| 140 if (!ReadSequence(&src, end) || | |
| 141 !ReadVersion(&src, end) || | |
| 142 !ReadAlgorithmIdentifier(&src, end) || | |
| 143 !ReadTypeHeaderAndLength(&src, end, kOctetStringTag, NULL) || | |
| 144 !ReadSequence(&src, end) || | |
| 145 !ReadVersion(&src, end) || | |
| 146 !ReadInteger(&src, end, &modulus_)) | |
| 147 return false; | |
| 148 | |
| 149 int mod_size = modulus_.size(); | |
| 150 READ_ASSERT(mod_size % 2 == 0); | |
| 151 int primes_size = mod_size / 2; | |
| 152 | |
| 153 if (!ReadIntegerWithExpectedSize(&src, end, 4, &public_exponent_) || | |
| 154 !ReadIntegerWithExpectedSize(&src, end, mod_size, &private_exponent_) || | |
| 155 !ReadIntegerWithExpectedSize(&src, end, primes_size, &prime1_) || | |
| 156 !ReadIntegerWithExpectedSize(&src, end, primes_size, &prime2_) || | |
| 157 !ReadIntegerWithExpectedSize(&src, end, primes_size, &exponent1_) || | |
| 158 !ReadIntegerWithExpectedSize(&src, end, primes_size, &exponent2_) || | |
| 159 !ReadIntegerWithExpectedSize(&src, end, primes_size, &coefficient_)) | |
| 160 return false; | |
| 161 | |
| 162 READ_ASSERT(src == end); | |
| 163 | |
| 164 | |
| 165 return true; | |
| 166 } | |
| 167 | |
| 168 void PrivateKeyInfoCodec::PrependInteger(const std::vector<uint8_t>& in, | |
| 169 std::list<uint8_t>* out) { | |
| 170 uint8_t* ptr = const_cast<uint8_t*>(&in.front()); | |
| 171 PrependIntegerImpl(ptr, in.size(), out, big_endian_); | |
| 172 } | |
| 173 | |
| 174 // Helper to prepend an ASN.1 integer. | |
| 175 void PrivateKeyInfoCodec::PrependInteger(uint8_t* val, | |
| 176 int num_bytes, | |
| 177 std::list<uint8_t>* data) { | |
| 178 PrependIntegerImpl(val, num_bytes, data, big_endian_); | |
| 179 } | |
| 180 | |
| 181 void PrivateKeyInfoCodec::PrependIntegerImpl(uint8_t* val, | |
| 182 int num_bytes, | |
| 183 std::list<uint8_t>* data, | |
| 184 bool big_endian) { | |
| 185 // Reverse input if little-endian. | |
| 186 std::vector<uint8_t> tmp; | |
| 187 if (!big_endian) { | |
| 188 tmp.assign(val, val + num_bytes); | |
| 189 std::reverse(tmp.begin(), tmp.end()); | |
| 190 val = &tmp.front(); | |
| 191 } | |
| 192 | |
| 193 // ASN.1 integers are unpadded byte arrays, so skip any null padding bytes | |
| 194 // from the most-significant end of the integer. | |
| 195 int start = 0; | |
| 196 while (start < (num_bytes - 1) && val[start] == 0x00) { | |
| 197 start++; | |
| 198 num_bytes--; | |
| 199 } | |
| 200 PrependBytes(val, start, num_bytes, data); | |
| 201 | |
| 202 // ASN.1 integers are signed. To encode a positive integer whose sign bit | |
| 203 // (the most significant bit) would otherwise be set and make the number | |
| 204 // negative, ASN.1 requires a leading null byte to force the integer to be | |
| 205 // positive. | |
| 206 uint8_t front = data->front(); | |
| 207 if ((front & 0x80) != 0) { | |
| 208 data->push_front(0x00); | |
| 209 num_bytes++; | |
| 210 } | |
| 211 | |
| 212 PrependTypeHeaderAndLength(kIntegerTag, num_bytes, data); | |
| 213 } | |
| 214 | |
| 215 bool PrivateKeyInfoCodec::ReadInteger(uint8_t** pos, | |
| 216 uint8_t* end, | |
| 217 std::vector<uint8_t>* out) { | |
| 218 return ReadIntegerImpl(pos, end, out, big_endian_); | |
| 219 } | |
| 220 | |
| 221 bool PrivateKeyInfoCodec::ReadIntegerWithExpectedSize( | |
| 222 uint8_t** pos, | |
| 223 uint8_t* end, | |
| 224 size_t expected_size, | |
| 225 std::vector<uint8_t>* out) { | |
| 226 std::vector<uint8_t> temp; | |
| 227 if (!ReadIntegerImpl(pos, end, &temp, true)) // Big-Endian | |
| 228 return false; | |
| 229 | |
| 230 int pad = expected_size - temp.size(); | |
| 231 int index = 0; | |
| 232 if (out->size() == expected_size + 1) { | |
| 233 READ_ASSERT(out->front() == 0x00); | |
| 234 pad++; | |
| 235 index++; | |
| 236 } else { | |
| 237 READ_ASSERT(out->size() <= expected_size); | |
| 238 } | |
| 239 | |
| 240 out->insert(out->end(), pad, 0x00); | |
| 241 out->insert(out->end(), temp.begin(), temp.end()); | |
| 242 | |
| 243 // Reverse output if little-endian. | |
| 244 if (!big_endian_) | |
| 245 std::reverse(out->begin(), out->end()); | |
| 246 return true; | |
| 247 } | |
| 248 | |
| 249 bool PrivateKeyInfoCodec::ReadIntegerImpl(uint8_t** pos, | |
| 250 uint8_t* end, | |
| 251 std::vector<uint8_t>* out, | |
| 252 bool big_endian) { | |
| 253 uint32_t length = 0; | |
| 254 if (!ReadTypeHeaderAndLength(pos, end, kIntegerTag, &length) || !length) | |
| 255 return false; | |
| 256 | |
| 257 // The first byte can be zero to force positiveness. We can ignore this. | |
| 258 if (**pos == 0x00) { | |
| 259 ++(*pos); | |
| 260 --length; | |
| 261 } | |
| 262 | |
| 263 if (length) | |
| 264 out->insert(out->end(), *pos, (*pos) + length); | |
| 265 | |
| 266 (*pos) += length; | |
| 267 | |
| 268 // Reverse output if little-endian. | |
| 269 if (!big_endian) | |
| 270 std::reverse(out->begin(), out->end()); | |
| 271 return true; | |
| 272 } | |
| 273 | |
| 274 void PrivateKeyInfoCodec::PrependBytes(uint8_t* val, | |
| 275 int start, | |
| 276 int num_bytes, | |
| 277 std::list<uint8_t>* data) { | |
| 278 while (num_bytes > 0) { | |
| 279 --num_bytes; | |
| 280 data->push_front(val[start + num_bytes]); | |
| 281 } | |
| 282 } | |
| 283 | |
| 284 void PrivateKeyInfoCodec::PrependLength(size_t size, std::list<uint8_t>* data) { | |
| 285 // The high bit is used to indicate whether additional octets are needed to | |
| 286 // represent the length. | |
| 287 if (size < 0x80) { | |
| 288 data->push_front(static_cast<uint8_t>(size)); | |
| 289 } else { | |
| 290 uint8_t num_bytes = 0; | |
| 291 while (size > 0) { | |
| 292 data->push_front(static_cast<uint8_t>(size & 0xFF)); | |
| 293 size >>= 8; | |
| 294 num_bytes++; | |
| 295 } | |
| 296 CHECK_LE(num_bytes, 4); | |
| 297 data->push_front(0x80 | num_bytes); | |
| 298 } | |
| 299 } | |
| 300 | |
| 301 void PrivateKeyInfoCodec::PrependTypeHeaderAndLength( | |
| 302 uint8_t type, | |
| 303 uint32_t length, | |
| 304 std::list<uint8_t>* output) { | |
| 305 PrependLength(length, output); | |
| 306 output->push_front(type); | |
| 307 } | |
| 308 | |
| 309 void PrivateKeyInfoCodec::PrependBitString(uint8_t* val, | |
| 310 int num_bytes, | |
| 311 std::list<uint8_t>* output) { | |
| 312 // Start with the data. | |
| 313 PrependBytes(val, 0, num_bytes, output); | |
| 314 // Zero unused bits. | |
| 315 output->push_front(0); | |
| 316 // Add the length. | |
| 317 PrependLength(num_bytes + 1, output); | |
| 318 // Finally, add the bit string tag. | |
| 319 output->push_front((uint8_t)kBitStringTag); | |
| 320 } | |
| 321 | |
| 322 bool PrivateKeyInfoCodec::ReadLength(uint8_t** pos, | |
| 323 uint8_t* end, | |
| 324 uint32_t* result) { | |
| 325 READ_ASSERT(*pos < end); | |
| 326 int length = 0; | |
| 327 | |
| 328 // If the MSB is not set, the length is just the byte itself. | |
| 329 if (!(**pos & 0x80)) { | |
| 330 length = **pos; | |
| 331 (*pos)++; | |
| 332 } else { | |
| 333 // Otherwise, the lower 7 indicate the length of the length. | |
| 334 int length_of_length = **pos & 0x7F; | |
| 335 READ_ASSERT(length_of_length <= 4); | |
| 336 (*pos)++; | |
| 337 READ_ASSERT(*pos + length_of_length < end); | |
| 338 | |
| 339 length = 0; | |
| 340 for (int i = 0; i < length_of_length; ++i) { | |
| 341 length <<= 8; | |
| 342 length |= **pos; | |
| 343 (*pos)++; | |
| 344 } | |
| 345 } | |
| 346 | |
| 347 READ_ASSERT(*pos + length <= end); | |
| 348 if (result) *result = length; | |
| 349 return true; | |
| 350 } | |
| 351 | |
| 352 bool PrivateKeyInfoCodec::ReadTypeHeaderAndLength(uint8_t** pos, | |
| 353 uint8_t* end, | |
| 354 uint8_t expected_tag, | |
| 355 uint32_t* length) { | |
| 356 READ_ASSERT(*pos < end); | |
| 357 READ_ASSERT(**pos == expected_tag); | |
| 358 (*pos)++; | |
| 359 | |
| 360 return ReadLength(pos, end, length); | |
| 361 } | |
| 362 | |
| 363 bool PrivateKeyInfoCodec::ReadSequence(uint8_t** pos, uint8_t* end) { | |
| 364 return ReadTypeHeaderAndLength(pos, end, kSequenceTag, NULL); | |
| 365 } | |
| 366 | |
| 367 bool PrivateKeyInfoCodec::ReadAlgorithmIdentifier(uint8_t** pos, uint8_t* end) { | |
| 368 READ_ASSERT(*pos + sizeof(kRsaAlgorithmIdentifier) < end); | |
| 369 READ_ASSERT(memcmp(*pos, kRsaAlgorithmIdentifier, | |
| 370 sizeof(kRsaAlgorithmIdentifier)) == 0); | |
| 371 (*pos) += sizeof(kRsaAlgorithmIdentifier); | |
| 372 return true; | |
| 373 } | |
| 374 | |
| 375 bool PrivateKeyInfoCodec::ReadVersion(uint8_t** pos, uint8_t* end) { | |
| 376 uint32_t length = 0; | |
| 377 if (!ReadTypeHeaderAndLength(pos, end, kIntegerTag, &length)) | |
| 378 return false; | |
| 379 | |
| 380 // The version should be zero. | |
| 381 for (uint32_t i = 0; i < length; ++i) { | |
| 382 READ_ASSERT(**pos == 0x00); | |
| 383 (*pos)++; | |
| 384 } | |
| 385 | |
| 386 return true; | |
| 387 } | |
| 388 | |
| 389 } // namespace crypto | |
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